I don't do an extra backup but I do check that my nightly backup completed correctly. If I'm feeling paranoid I do a test restore of a single randomly selected file.

There has been a longstanding bug with Apple's Updater (note, however, I have removed unsanity's application program enhancer from all my machines). There's a low but non-zero probability that it will botch an update; the probability rises sharply if you're doing anything during the update process or if another users is logged on at the same time. The restart reduces that risk substantially, as does the plain admin account.

I don't repair privileges. Everyone I read feels that's pointless.

Since I have no recognized problems with OS X 10.4.10 I'm in no great hurry to update*.

*iPhoto 7.1 is crashy. I hope the combination of 10.4.11 and iPhoto 7.11 will help.

Update 11/15/07: Some hints in Apple's release notes and user experiences suggest 10.4.11 may have the same trouble with input manager hacks (application program enhancer mostly) as 10.5 has. I recommend checking for APE as described in the APE uninstall guidelines. Then uninstall it.

After the update, if you absolutely can't live without APE, do your research prior to reinstalling the very latest version.